I sincerely want to thank everyone for their thoughtful responses. My son did try to advocate for himself. He wrote the teacher a very persuasive email explaining where he thought there was a miscommunication. She basically rolled her eyes at him. He has learned his lesson that he really needs to pay attention to the details with this particular teacher and to be extremely proactive when it comes to assignments. He’s depressed about what he feels is an injustice, but he will live. Hopefully this B- will not drag down his final grade. If it does, so be it–he’s got better grades in his other classes.